A hard disk drive (HDD) is a device for recording on a disc or records data onto the disc using a read/write head. The hard disc drive is being widely used as an auxiliary memory device of a computer system owing to its capability to access a great amount of data at a high speed.
Generally, the HDD comprises a disc serving as a recording medium where data is recorded and stored, a spindle motor configured to rotate the disc at a high speed, and a head stack assembly (HSA) having a read/write head configured to record data onto the disc and read out data recorded on the disc.
The HSA rotates by a voice coil motor (VCM) around a rotation shaft, which acts as a pivoting shaft. The HSA includes an actuator arm rotatably coupled to the rotation shaft, a slider having a read/write head mounted thereon, and a suspension installed at the actuator arm and configured to support the slider to be elastically biased towards the surface of the disc. A sub-assembly of the read/write head, the slider, the suspension, etc. is called a Head Gimbal Assembly (HGA).
The suspension may include a base plate, a lload beam, a hinge for connecting the base plate and the load beam to each other, and a flexure. Especially, the end part of the flexure to which the slider is attached is called ‘gimbal’. The gimbal is a very important part in relation to Pitch Static Angle (PSA), Roll Static Angle (RSA), and pitch/roll stiffness for stable flying of the slider.
The PSA indicates an angle between the loadbeam and the flexure in a pitching direction, and the RSA indicates an angle between the load beam and the flexure in a rolling direction.
Once the HDD is driven, the slider can be loaded on the disc from a ramp. For stable flying, the slider should be in a particular attitude. If an initial angle of the slider is out of the range of a preset value, problems may occur in regards to fly height and long term reliability.
The PSA and RSA are factors used determining an initial attitude of the slider when the slider flies. Accordingly, the PSA/RSA is strictly controlled to have specifications defined during Head Gimbal Assembly (HGA) processing for coupling the slider to the suspension, during Head Stack Assembly (HSA) processing for coupling the suspension to the actuator arm, etc., and so on.
In one example, the RSA has a median value of 0°, and the PSA has a constant target value. If the PSA is greater than the preset value, the fly height (FH) may be increased, and reliability may be lowered due to scratches generated when loading/unloading the head.
The PSA/RSA, an important specification of the suspension, is determined when manufacturing the suspension. However, the PSA/RSA may be severely changed during the HGA/HSA processing. In a serious case, the PSA/RSA may deviate from preset target values. In this case, it may be impossible to compensate for the PSA/RSA.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.